Prior art converter designs make use of a standard common-emitter transistor D.C.-D.C. converter having the collector-emitter paths of two transistors connected together in a current loop including an output transformer. Such converters employ a base drive circuit including a feedback winding coupled to the base of each transistor to effect oscillation of the converter. Prior art D.C.--D.C. converters employ a fast-rise time square wave circuit to drive the bases of the common-emitter coupled transistors. In such a conventional converter circuit, the fast-rise base driving waveform produces a corresponding fast-rise collector waveform which, in turn, produces high frequency harmonics of the switching waveform which are difficult to filter out and which propagate through the circuit to the utilization system. Prior art efforts to eliminate the high frequency harmonics by increasing the rise-time of the base drive waveform, raised the alternate problem of producing dead-zone or cross-over distortion in the output waveform. This cross-over distortion changes significantly when the temperature of the semiconductor components in the circuit varies substantially. The efficiency of operation of such a prior art converter is substantially impaired when exposed to temperature extremes, particularly higher temperatures, while the cross-over distortion becomes more pronounced at the lower temperatures.